... cavity. They are generally more or less covered and protected by a calcareous shell, which may be univalve, bivalve, or multivalve. Formerly the Brachiopoda, Bryzoa, and Tunicata were united with the Lamellibranchiata in an artificial group called Acephala, which was also included under Mollusca. ...

... cavity. They are generally more or less covered and protected by a calcareous shell, which may be univalve, bivalve, or multivalve. Formerly the Brachiopoda, Bryzoa, and Tunicata were united with the Lamellibranchiata in an artificial group called Acephala, which was also included under Mollusca. ...